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Why Did my Betta Fish Die? (11 Common Reasons)

Sarah Psaradelis

By Sarah Psaradelis

betta fish tank

It can be disheartening to find out your betta fish has died, especially when you do not know why. Finding the cause of death can bring closure and peace to the situation and luckily for you, it is simple to determine why your fish died and there are a lot of common mistakes that can cause them to pass. Betta fish can live an average of 2 to 4 years old, which is quite old! It is not uncommon for well-cared-for bettas to live up to 5 years.

If you are looking for reasons that your betta fish could have potentially died from, look no further than this article which will inform you on the most popular reasons a betta fish may die.aquarium plant divider

The 11 Common Reasons your Betta Fish Died

From each reason, many possibilities stem from. For instance, poor water quality can lead to several different infections that your betta could have died from and only you can compare your betta’s symptoms to the various diagnosis lists to see if they match and determine if that potentially killed your betta fish. Sometimes a betta fish may die with no visible symptoms, or even delayed symptoms that only arise towards the very end.

1. An uncycled tank (ammonia, nitrite, nitrate poisoning symptoms)

aquarium cycle_hedgehog94_Shutterstock
Image Credit: hedgehog94, Shutterstock

Before you even get a betta, you should first cycle the tank to get a good establishment of beneficial bacteria. This process is known as the nitrogen cycle and is an important first step for all new aquariums. Cycling a tank can take anywhere between 4 to 8 weeks and the process ensures that toxic levels of ammonia and nitrite are quickly turned into nitrate which is non-toxic to fish and invertebrates at low levels. Without the water parameters being at 0ppm ammonia and nitrite, your fish can suffer from the build-up of toxins. This is the most common cause for new fish to die.

Ammonia poisoning: The fish sustains red or black streaks and black or red patches along the body. You may notice lethargy, loss of appetite, and clamped fins. Secondary infections can occur from the toxin burning through the slime coat. Ammonia levels should never reach higher than 0ppm (parts per million).

Nitrite poisoning: Commonly causes brown blood disease. Symptoms include brown gills, listlessness, gasping at the surface, and sudden death. White or opal bettas may develop visible brown patches. Nitrate toxicosis turns the fish’s blood brown from an increase in methemoglobin and renders the blood unable to carry oxygen throughout the body. Levels should never exceed 0ppm.

Nitrate poisoning: A curved body with weight loss, loss of appetite, clamped fins and red streaks are all common symptoms of excess nitrate levels in the water. A heavily planted tank and weekly water changes should never exceed 25ppm.

Tip: Use a liquid testing kit to help determine the levels of toxins in the water!

2. Incorrect housing

betta fish in bowl_Piqsels
Image Credit: Piqsels

It is common for new hobbyists to throw a betta fish in a bowl or vase and assume that the fish will be happy. Only to find them wasting away in their bowl and displaying no activity other than pacing. Small bodies of water cause toxins to build up quickly in the water, which will ultimately hurt your fish. These small spaces also cause immense stress to the betta, especially since they cannot see beyond the curved wall as they distort their natural vision. Stress can bring on an abundance of illnesses and generally shorten your betta’s lifespan by years. It is not uncommon for a betta to suddenly die when they are in poor housing situations.

3. Bad genetics

Silver and orange betta fish
Image Credit: ivabalk, Pixabay

Since most betta owners purchase betta fish from pet stores, the fish are bound to have issues connected to their poor breeding. Pet stores get their stock from mass fish breeding farms where the bettas are bred for quantity and not quality. Poor genetics can cause your betta to live half the potential lifespan and can cause them to perish with absolutely no symptoms. It is quite common for pet store bettas to develop tumors and die a few weeks after.

4. Old age

Image Credit: Ron Kuenitz, Shutterstock

If you have a good setup for your betta and they have been with you for quite some time now, but you notice them slowing down and not as active as they used to be then your betta may be getting old. Unfortunately, as soon a betta starts displaying symptoms of their age (2–5 years) then they typically only have a few weeks left and it is not uncommon to only realize your betta was displaying old age behavior after they have already died.

5. Disease

sick betta fish
Image Credit: Wirestock Creators, Shutterstock

Even the healthiest of betta fish are prone to disease. Pathogens enter the tank through dirty hands, sharing tank equipment between different tanks, adding in a new fish, or even on certain aquatic plants. Each disease is treatable due to the large selection of medications for various diseases. Yet sometimes the disease is too stubborn and does not react to treatment and unfortunately can kill the betta.

6. Dropsy

betta fish surface of water looking up
Image Credit: Ivabalk, Pixabay

This is not so much of disease itself; it is the result of prolonged and serious organ damage. Dropsy can kill a fish overnight and the main symptoms are swelling of the abdomen and pine coning (the scales stick out and resemble a pinecone when viewed from above). Dropsy is hard to treat and can be caused by various pathogens that have taken a toll on the internal organs.

7. Suffocation

group of female betta fish in tank
Image Credit: Hobi Atok, Shutterstock

All fish require a source of fresh oxygen in the water. This is created by constant and rough surface movement from various aeration systems such as air stones, air rings, bubble makers, and wavemakers. This results in gas exchange from the surface and oxygen makes its way into the water column. If you have your betta in a bowl or vase, the surface area is reduced minimal oxygen enters the water. If your tank lacks an aeration system and you noticed your betta gasping at the surface a lot, then it could be that your betta fish has suffocated. Aeration systems should run 24/7 in a tank.

Fun fact: Betta fish have a labyrinth organ that acts as a lung. They will gulp once at the surface a few times a day to refill it. This should not be confused with gasping which is a frequent and continuous act linked to low amounts of dissolved oxygen!

8. Medication overdose

sick red betta fish
Image Credit: Yasin Fadlilah, Shutterstock

Most aquatic medications are safe even with minor changes to the dosage directions, however, certain medications have unwanted side effects and can be harmful in certain doses. Medication dosages are found on the label or package of the medication and typically work according to how many liters or gallons the tank is. If you have incorrectly dosed your betta fish, it can cause a layer of toxins to build upon their gills and suffocate them. It can also accumulate in toxic amounts and be dissolved into the bloodstream which further causes death. The same applies to mixing incompatible medications and depriving the treatment tank of a portable aeration system.

9. Chlorine burn

glass aquarium tank
Image Credit: Unsplash

All water needs to be dechlorinated by a high-quality water condition before you place a betta fish inside. The amount of chlorine depends on the water source, but tap, borehole, bottled, and RO water should be dechlorinated. When you do water changes, the new water should also be conditioned and prepared for your betta fish. Chlorine burns appear as black patches. You may also notice rapid breathing and death within 3 hours.

10. Injuries

sick betta fish
Image Credit: Tutik_P, Shutterstock

Sharp decorations and rough fake plants are major causes of betta fish injuries. These materials tear your betta’s fins which can cause an assortment of bacterial infections that can be life-threatening. Your betta can also sustain injuries from tank mates like other bettas, fin-nipping fish, and other unsuitable tank mates. Your betta can die indirectly from the infections that developed from the injured site.

11. Freezing

blue betta fish in aquarium
Image Credit: Lapis2380, Shutterstock

Bettas are strictly tropical fish, meaning they require a heater to thrive. The temperature should be kept between 77°F to 82°F. This is the temperature bettas are most comfortable. If your betta has unstable temperatures that continuously fluctuate, it can cause stress that will lead to an illness. Coldwater can cause fungal infections or ich (white spot disease), which can easily be cured by gradually raising the temperature with a pre-set heater. If your betta was in a tank with no heater or the heater failed, then it can catch a chill and pass from low immunity.

Related Read: 7 Best Heaters For 5 Gallon Betta Tanks – Reviews & Top Picks 2021

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Basic Betta Survival Tips

Learning from past mistakes is the first part of healing from the loss of your betta fish. Everyone makes mistakes and if you feed your betta fish’s death was your fault, do not blame yourself too much! It is best to correct any mistakes and do better next time.

  • Ensure that your betta is in a tank of at least 5 gallons. 10 to 20 gallons is ideal and best suited for beginners as the large body of water provides more room for error.
  • Cycle the filter and tank before placing your betta inside.
  • Test your water regularly and conduct weekly water changes.
  • Swap out fake plants and decorations for live plants and silicone products.
  • Make sure the heater is always working and regularly check the thermometer to ensure the temperature is appropriate.
betta inside aquarium_Pixabay
Image Credit: Jumpstory

You might also be interested in: How Much Does a Betta Fish Cost? Everything You Need to Know!

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Wrapping it Up

Dealing with the loss of your betta will be hard, but just remember that you did the best you could! Fishkeeping has its ups and downs and it is common for fish to die throughout the hobby. Always ensure that you research and provide the best home that you can for your betta fish and you should expect to raise a healthy betta fish for a few years.

Featured Image Credit: Kosit Pajuthai, Shutterstock

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